Table of Contents
4.8.3
Power Control Logic
The power on sequence can be initiated when a valid battery voltage is applied (VBATT>3.1).
One of following conditions start the Power Up sequence.
1.
Power key is pushed for more than 1,000 ms
2.
Application of a charger voltage EXT_PWR > 4.0V
3.
Real Time Clock alarm generated by U100 (SGOLD) RTCOUT=1
The Power Up sequence is as follows:
1.
U304 band gap reference is activated.
2.
U304 checks VBATT voltage. If VBATT > 3.1 then power-up, Else check for VBATT while power-up event is valid.
3.
The following U304 regulators are enabled in sequence: VRF2, SDBB, VLBB2, VLBB1, VINT, VANA, VSIM1, V28, VSD,
VUSB.
4.
After U304 VINT is enabled, U300 VLBB3 is also enabled.
5.
After U304 VUSB is enabled, U304-41 (INTOUT) will go low followed by U304-48 (RESET_N) going high releasing U100
SGOLD from reset.
6.
U100 boot code will determine if the power-up sequence is valid. If valid then provide clock to U200 (13MHz and 32kHz)
and release U100 from reset (AP_RST); Else send ALL_OFF command to U304 to power-down the system.
7.
U200 power-up to complete the turn-on sequence.
The power-down sequence of the phone is as follows:
1.
Power-down sequence is initiated by the detection of a valid SW428 ON/OFF key press or a low battery voltage condition
has been detected.
2.
U200 determines that a valid power-down sequence was detected.
3.
U200 disables both active hardware and software application.
4.
After U200 power-down sequence is completed, a command to U100 is sent to disable U304.
5.
U100 initiates its power-down sequence then resets U200 and remove clock.
6.
After U100 power-down sequence is completed, an ALL_OFF command to U304 is sent to disable all regulators.
PROVISIONAL ISSUE
− 4-17 −
Table of Contents
